1. Field of the Invention
The present invention relates to a pressed car ceiling attached to the underside of the roof panel in the car.
2. Prior Art
The pressed car ceiling is attached to the underside of the roof panel in the car to make the inside of the car beautiful, enhance the safety of persons in the car and attain adiabatic and sound insulation effects.
The pressed car ceiling 1 shown in FIG. 1, for example, is formed by press-forming a base material 2 of corrugated cardboard to meet the inner outline of the roof panel 5 according to the hot press method and heat-pressing a surface skin material 3 on the underside of the molded corrugated cardboard base material 2 with a layer 4 of heat melting adhesive interposed between them. The pressed car ceiling 1 thus formed is positioned along the roof panel 5, keeping its corrugated cardboard base material 2 upside, and fixed to a roof rail 7 by welts or garnishes 6 at its peripheral rim.
In the case of the conventional pressed car ceilings, the heat melting adhesive layer 4 is intended only to put the corrugated cardboard base material 4 and the surface skin material 3 together and it is therefore provided thin and uniform between them.
The pressed car ceiling 1 discharges moisture contained in it in the process of press-forming the corrugated cardboard base material 2 and internal stress is caused and remains at its peripheral portion which is more deeply curved inward. When the corrugated cardboard base material has absorbed ambient moisture after the press-forming therefore, this remaining internal stress forces its peripheral portion which has been curved inward to deform outward to return to its original shape. A so-called spring-back occurs. When this spring-back occurs, its peripheral portion is not fitted to the inner outline of the roof, panel 7, as shown by a broken line 1' in FIG. 1, and it cannot be attached to the roof panel 7 accordingly. This spring-back may occur at its other portions which have been more deeply curved inward.